Oral Therapeutic Vaccination with Streptococcus sobrinus Recombinant Enolase Confers Protection against Dental Caries in Rats

Dentalcariesisamongthemoreprevalentchronichumaninfectionsforwhichaneffectivehumanvaccinehasnot yet been achieved. Enolase fromStreptococcus sobrinushas been identified as an immunomodulatory protein. In the present study, we used S. sobrinus recombinant enolase (rEnolase) as a target antigen and assessed its therapeutic effect in a rat model of dental caries. Wistar rats that were fed a cariogenic solid diet on day 18 after birth were orally infected with S. sobrinus on day 19 after birth and for 5 consecutive days thereafter. Five days after infection and, again, 3 weeks later, rEnolase plus alum adjuvant was delivered into the oral cavity of the rats. A sham-immunizedgroupofratswascontemporarilytreatedwithadjuvantalone.IntherEnolase-immunizedrats, increased levels of salivary IgA and IgG antibodies specific for this recombinant protein were detected. A significant decrease in sulcal, proximal enamel, and dentin caries scores was observed in these animals, compared with sham-immunized control animals. No detectable histopathologic alterations were observed in all immunized animals.Furthermore,theantibodiesproducedagainstbacterialenolasedidnotreactwithhumanenolase.Overall, these results indicate that rEnolase could be a promising and safe candidate for testing in trials of vaccines against dental caries in humans. Dental caries is one of the most prevalent infectious diseases in humans [1, 2] and has been associated with major clinical complications, such as infective endocarditis [3–5]. The World Oral Health Report 2003 [6], published by the World Health Organization, indicates that dental caries is a major health problem in most industrialized countries, affecting children, adolescents, and adults. Approximately 5% of the total expenditure for